The primary objective of this project is the bioregulation of the important mosquito vectors of diseases in Pakistan. Genetic manipulation of laboratory-reared mosquito populations has produced strains with reduced reproduction potential and/or vectorability. Emphasis is placed on three species: Culex tritaeniorhynchus which transmit Japanese encephalitis, West Nile and Chikungunya viruses, and the major Pakistani malarial vectors, Anopheles stephensi and An. culicifacies. Several test areas have been thoroughly studied ecologically for the past 3 years and now serve as sites for the altered, non-vector or semisterile mosquito release. This year a clinical component is being established to monitor the changes in disease patterns that may arise from the mosquito release program.